Biomass gas and biomass charcoal preparation system

ABSTRACT

The present invention relates to a biomass gas and biomass charcoal preparation system, including three successive working units: a feeding unit, a pyrolysis reaction unit, and a discharging unit, and further having a pyrolysis reaction control system. The pyrolysis reaction unit has a pyrolysis reaction body. The pyrolysis reaction body is provided therein with a helical propulsion device and an air supply device. The pyrolysis reaction body is a rectangular cavity having a metal shell. The cavity of the pyrolysis reaction body is divided into two parts: an upper part and a lower part that are separable. In the present invention, the pyrolysis reaction body is provided therein with a thermal insulating layer, which effectively separates the metal shell from a high-temperature reaction medium, so requirements for the heat resistance of the material of the cavity of the pyrolysis reaction body are lowered, a common carbon steel material can be used and the cost is reduced, and the metal shell is effectively relieved of thermal deformation, and heat loss is reduced; the pyrolysis reaction body is divided into an upper part and a lower part, so it is easier to disassemble wearing parts on the bottom of the reaction body to facilitate maintenance and replacement.

FIELD OF INVENTION

The present invention relates to biomass systems and in particular to a biomass gas and biomass charcoal preparation system.

BACKGROUND

China is challenged to satisfy the ever increasing demand for energy by it's growing population and is faced with the heavy burden of improving air quality that has resulted because of the use of un-renewable energy sources. Due to decreasing fossil fuel reserves, large fluctuations in oil prices, concerns regarding the security of existing energy sources, and the problem of global warming, development of clean and renewable energies has become an important global issue indicating that the renewable energy industry has the potential for high growth. The ever increasing global demand for energy, and in particular environmentally friendly energy, such as biomass derived energy, is driving the development of renewable energy technologies such as, biomass gasification power generation, biomass hydrogen energy, and biomass green liquid fuel for use today and in the future. There is an abundance of renewable biomass energy sources in China, and large-scale adoption of the use of the biomass renewable energy by the nation will reduce CO2 emissions and facilitate the improvement of the environment.

Biomass refers to organic matter that can be converted into a potential energy source such as fuel. Biomass includes plants, microorganisms and animals feeding thereon as well as plant and animal waste. Currently the global yield of biomass is approximately 146 billion tons per year, including 30 billion tons of biomass produced in rural areas annually Biomass is estimated to be the fourth major global energy source preceded by fossil fuels such as petroleum, coal, and natural gas. Biomass has drawn world wide attention due to, for example, its ability for high yield, storability, and carbon cycle. There are abundant biomass resources in China, with the total amount of resources not less than 3 billion tons of dry matter per year; which is equivalent in terms of energy potential to 1 billion tons of oil per year—approximately 3 times the current oil consumption by China There are more than 700 million tons of crop straw and agricultural byproducts produces each year, of which, 30% is used as feed, fertilizers, and industrial raw materials, wherein approximately 60% thereof can be used as an energy source. (Zhu Xifeng and Lu Qiang, Fast Pyrolysis of Biomass for Producing Bio-oil [J], Science & Technology Review, 2007, 25(27): 69-75.) For example, since 2005, the annual yield of rice in China has been more than 180 million tons four consecutive years in a row. The main byproduct of processing rice is rice husks. Since rice husks make up approximately 20% of rice in weight, the annual yield of rice husks is more than 36 million tons, which is approximated to be equivalent to more than 18 million tons of standard coal in potential energy.

Chinese utility model patent CN201020653868.9, “Biomass Fuel Gas and Biomass Charcoal Preparation System with Accurate Control”, Cui et al, discloses a biomass gas and biomass charcoal preparation system wherein the temperature of the biomass raw material during pyrolysis can reach temperatures greater than 500° C. and the temperature of the of the metal cavity of the reaction body reaches between 500-600° C. The reference teaches that the metal cavity shell comprises stainless steel in order to ensure the relative stability of the reactor. Stainless steel is a more expensive material than other metallic materials, adding to the cost of the system. As the stainless steel material is at high temperature for a long time, it easily deforms, causing deformation of the entire reaction body and affecting production consistency. Furthermore, as the cavity of the reaction body is of an upper-cover type and comprises multiple parts, replacing, the lower portion of the cavity often due to deformation is labor intensive. Many cavity parts must be disassembled to replace the lower portion with a new one and then reassembled. Each disassembly increases the chance of introducing human error which may decrease the system's stability and reliability

It would be advantageous to overcome some of the disadvantages of the prior art.

SUMMARY OF THE EMBODIMENTS OF THE INVENTION

In accordance with the invention there is provided a system comprising A biomass as and biomass charcoal preparation system, including three successive working units: a feeding unit (1), a pyrolysis reaction unit (2), and a discharging unit (3), and further having a pyrolysis reaction control system (4), wherein the feeding unit (1) has a helical feeding device (11) with helical blades provided at varying densities; the pyrolysis reaction unit (2) has a pyrolysis reaction body (21), and the pyrolysis reaction body (21) is provided therein with a helical propulsion device (22) and an air supply device (23); and the discharging unit (3) has a helical discharging device (32) and an air feeding system (33); the pyrolysis reaction body (21) is a rectangular cavity having a metal shell; and the air supply device (23) has a porous box disposed on the bottom of the pyrolysis reaction body (21), characterized in that the cavity of the pyrolysis reaction body (21) is divided into two parts: an upper part and a lower part that are separable.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments will now be described in conjunction with the following drawings, wherein like numerals refer to elements having similar function, in which:

FIG. 1 is a simple diagram of a biomass as and biomass charcoal preparation system according to an embodiment of the invention.

FIG. 2 is a sectional view of a pyrolysis reaction body according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION

The following description is presented to enable a person skilled in the art to make and use the invention, and is provided in the context of a particular application and its requirements. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the scope of the invention. Thus, the present invention is not intended, to be limited, to the embodiments disclosed, but is to be accorded the widest scope consistent with the principles and features disclosed herein.

A biomass gas and biomass charcoal preparation (BGBCP) system according to an embodiment of the invention is shown in FIG. 1. The BGBCP system comprises a feeding unit 1 that receives and prepares raw biomass material for processing. Coupled to the feeding unit 1 is pyrolysis reaction unit 2 that heats the raw biomass material for decomposition and the collection of biomass gas and biomass charcoal. The BGBCP system further comprises discharging unit 3 coupled to pyrolysis reaction unit 2 which receives, cools and removes the biomass charcoal produced during the pyrolysis reaction. Finally, the BGBCP system comprises control system 4 for monitoring the pyrolysis reaction and adjusting elements of the BGBCP system to maximize the system's biomass gas and charcoal production.

Feeding unit 1 has helical feeding device 11 and feeding bin 12 coupled therewith. Raw biomass material put into helical feeding device 11 is compressed as it travels along the screw rod (not shown) thereof toward feeding bin 12. Feeding bin 12 is, for example, a conduit that transfers compressed raw biomass material received from the helical feeding device 11 to pyrolysis reaction unit 2. Optionally, helical feeding device 11 has no helix on a portion of the screw rod thereof (not shown) proximate feeding bin 12. Optionally, the pitch between blades of the helical feeding device 11 vary.

Pyrolysis reaction unit 2 comprises pyrolysis reaction body 21 of rectangular shape having metal shell 8 with a bottom wall and cavity 9 therein. Optionally, pyrolysis reaction body 21 is other than of rectangular shape. Helical propulsion device 22 mounted within cavity 9 proximate the bottom wall moves compressed raw biomass material received from feeding bin 12 within pyrolysis reaction body 21 as it is heated therein to biomass charcoal outlet port 25, to which it is coupled. Biomass gas produces during the pyrolysis reaction is expelled from biomass as outlet port 26. Helical propulsion device 22 has lateral rake teeth along it's shaft wherein the number of lateral rake teeth decreases in high-temperature locations within the pyrolysis reaction body 21. In other words, the pitch between the helical blades increases in high-temperature locations. Furthermore, hot air passes through the shaft to aid in the pyrolysis reaction. In this embodiment, helical propulsion device 22 is mounted on the bottom of the pyrolysis reaction body 21. Optionally, helical propulsion device 22 has two helix’ to move the biomass material within pyrolysis reaction body 21 as shown in FIG. 2.

Still referring to FIG. 1, pyrolysis reaction body 21 comprises thermal insulating layer 28 that insulates the interior walls of metal shell 8 other than the bottom wall. Thermal insulating layer 28 aids in separating the metal shell 8 from a high-temperature reaction medium. Insulating the metal shell 8 from high temperatures aids in minimizing the requirements fir heat resistance of metal shell 8 and thus the cost of the material thereof. For example, a low cost common carbon steel material is used. Furthermore, insulating the metal shell 8 from high temperatures aids in preventing thermal deformation thereof and heat loss in the BGBCP system, thus increasing system efficiency. Optionally, thermal insulating layer 28 comprises a ceramic fiber cotton. Optionally, thermal insulating layer 28 comprises a light-weight, high-temperature resistant and corrosion resistant thermal insulating material.

Pyrolysis reaction body 21 comprises air supply device 23 having outlet ports that expel hot air is mounted proximate the un-insulated wall and helical propulsion device 22. The expelled hot air enters the pyrolysis reaction body 21 and heats the raw biomass material causing the pyrolysis reaction. Optionally, the outlet ports are spaced apart from each other at various distances.

Water cooling jacket 31 is mounted on the exterior of helical discharging device 32 for cooling the biomass charcoal produced during the pyrolysis reaction. Helical discharging device 32 is coupled to air feeding system 33, comprising a cyclone separator having an oil screen tar capturing and sorting device (not shown). Tar particles having a larger density than that of the biomass charcoal are cyclone separated from the biomass charcoal and are extracted by the oil screen.

Control system 4 comprises air supply control valve 42 coupled to air supply device 23 for controlling the temperature and pressure of air provided thereto. Control system 4 also comprises material level height adjustment device 43 that adjusts the height of the biomass materials within pyrolysis reaction body 21 and is mounted therein proximate feeding bin 12. Material level height adjustment device 43 comprises an adjusting plate that extends downwards for adjusting the height of the materials passing through the adjusting plate. Helical propulsion speed regulator 41 comprises a variable-frequency speed regulator for controlling the speed of helical propulsion device 22. Controllable electric furnace heating wires are mounted, proximate the biomass gas outlet 26 and inside biomass charcoal outlet 25 respectively to prevent tar from coking. Coupled to the pyrolysis reaction body 21 is hot air jacket 24 comprising hot air guiding blades and heat transfer ribs. Gas mixing device 44 mounted within the cavity of the pyrolysis reaction body 21 on the wall opposing the bottom wall, comprises two baffles disposed adjacent to each other having a gap there between wherein gases collide and mix together. Reaction monitoring device 45 coupled to pyrolysis reaction body 21, comprises a pressure meter, an air flow meter, and a thermometer (not shown). Control system 4 monitors the pyrolysis reaction via the sensors of the reaction monitoring device 45 and adjusts the controllable devices of the BGBCP system to maximize the system's biomass gas and charcoal production.

Pyrolysis reaction body 21 further comprises an upper portion 5 detachably coupled to lower portion 6. For example, upper portion 5 is detachably coupled to lower portion 6 via mechanical bracket 27 as shown in FIG. 1. Maintenance and/or repair of components inside pyrolysis reaction body 21 is simplified and/or less labor intensive in comparison to a pyrolysis system comprising a reaction body that is fixedly assembled. For example, in use, the temperature of the cavity of the pyrolysis reaction body 21 is controllable to remain below 100° C. mainly due to the presence of the thermal insulating layer, however, the temperature of air supply device 23 reaches approximately 300° C. due to the absence of a thermal insulating layer on the bottom wall and thus often requires repair. The decoupling of lower portion 6 from upper portion 5 is convenient as is allows for easy access to the air supply device for maintenance and replacement as it is coupled to the lower portion 6 of pyrolysis reaction body 21.

The embodiments presented are exemplary only and persons skilled in the art would appreciate that variations to the embodiments described above may he made without departing from the scope of the invention. 

What is claimed is:
 1. A biomass gas and biomass charcoal preparation system, including three successive working units: a feeding unit (1), a pyrolysis reaction unit (2), and a discharging unit (3), and further having a pyrolysis reaction control system (4), wherein the feeding unit (1) has a helical feeding device (11) with helical blades provided at varying densities; the pyrolysis reaction unit (2) has a pyrolysis reaction body (21), and the pyrolysis reaction body (21) is provided therein with a helical propulsion device (22) and an air supply device (23); and the discharging unit (3) has a helical discharging device (32) and an air feeding system (33); the pyrolysis reaction body (21) is a rectangular cavity having a metal shell; and the air supply device (23) has a porous box disposed on the bottom of the pyrolysis reaction body (21), characterized in that the cavity of the pyrolysis reaction body (21) is divided into parts: an upper part and a lower part that are separable.
 2. The biomass gas and biomass charcoal preparation system according to claim 1, characterized in that an interface (27) between the upper part and the lower part of the cavity of the pyrolysis reaction body (21) is opened on the lower part of the cavity, so that the bottom of the cavity together with the air supply device (23) can be detached from the pyrolysis reaction body (21) during separation.
 3. The biomass gas and biomass charcoal preparation system according to claim 1, characterized in that an interface (27) between the upper part and the lower part of the cavity of the pyrolysis reaction body (21) is opened at the end of the lower part of the cavity.
 4. The biomass gas and biomass charcoal preparation system according to claim 2, characterized in that an inner surface of the cavity other than a bottom surface of the pyrolysis reaction body (21) is provided with a thermal insulating layer (28).
 5. The biomass gas and biomass charcoal preparation system according to claim 3, characterized in that the thermal insulating layer (28) is made of a light-weight, high-temperature resistant and corrosion resistant thermal insulating material. 